Hollow article and method of enameling it



Oct. 23, 1934. A. w. MACKERT HOLLOW ARTICLE AND METHOD OF ENAMELING IT IN VE N TOR flzaze rbl/wc/rzer a 3 w A TTORNE Y Filed July 22, 1953 Patented Oct. 23, 1934 'EUiNdTED :srAT-Es OFF-ICE 1978.213 HOLLOW ARTICLE AND METHOD or" yEN'AMEIiING IT' Albert 'WQJMackert, Lakewood, -.;0hio, r assignor it? The 0hl0 F011nd1y .00., Qleveland, .Ohio, a cor-- .poration of Ohio Application .l'ulyl22, 1933,"-Serial No."68-1,794

10 Claims.

My invention'pertains to a hollow article and tothe method of enameling it. 'The drawing merely exemplifies application of theprinciples of my "invention to. acommon form of water heater casing.

My employment with an enamelingcompany has causedme-duringthepastfew years of growing popularity of enameled articles, to become familiar withwarious difficulties and problems,

"respectively for preventing warpage or other distortion of sheet metal articles or parts thereof duringtheprocess of enameling and for reducing the cost of the enameling procedure. Onetype of water heatercasing comprises a circular base, 'circular top, semi-cylindrical connecting wall and serhi-cylindrical door hinged to' the wall.

Heretofore, so far as my knowledge extends, the

which if overcome'by forcing the door into closed rposition, caused resultant distortion of theassembled heater casing. The -co-pen ding patent application of Henry Trenkamp, Jr., filed August 18, 1932 hearing Serial No. 629,320 discloses one improvingefiort at our plant to controlithe variametal piecesto be enameled. l i l It is evident that to apply enamel coatings to separatepieces of an articleto be assembled involves considerably more handling and" requires considerably more "drying space. The same 1 dis- -advantage appliesduring the baking and cooling might be enamel-coated and burned with a 'savmg of time and money I have ':.of:heatatherethrouglrduring;the baking operation.

.After completion of theenameling'the beads may "be 'optionallymeduced-or entirely removed.

succeeded inadoing sozwith an exceedingly simple discover-y which utilizes the limited resiliency of the assembled parts. g I

Some marketed heater jackets had the two semi-cylindrical halves stamped by the same die in ordertoreducetool cost,but such jacket walls left openings along their vertical edges which .lessened commercial popularity. On 'the other "hand, when .the meeting edgeswereflange-offset to interlockwithan overlap of onebythe other .as preferred "by the 'trade, the difiiculty was (iCl. 91- 73) presented .of spraying a uniform coating to all parts of the assembled'heater, specifically, avoiding a surplus accumulation of enamel along the .interfitting edges which would improperly bake,

occasion a bind when the door was finally to be 69 opened and frequently rupture the enamel coating..-along,such edges and result in an unsightly appearance. .Moreoventhe necessary clearance .requiredbetween the edges of the door opening would permit .warpage or distortion and cause i either a binding action or an overall distortion.

, The general object ofmyinvention, which has been. successfully realized in commercial productionj-ha's been to eliminate the difilcultieshere- Ttoforeencounteredand to do so with a simple,

economical and expeditious practice.

Taking advantage-of the resilience of arcuate "portions ofthe'base and top whichproject beyond the two edges of their connecting wall and of the ,resiliencyofthe edges of thehinged door, Iprovi/"idelsuch edges. which are to be appositioned when the door is closed, with ,predeterminately .spacediwedges actually in the form of small sphericallyfspacedbeads. Such beads are shown in the drawing to be formed on the four edges of the door,.but it is tobe understood that they mightbe onithe edges of the connecting wall which are to be overlapped or on the arcuate projecting .ed'geportions of the base and top so thatthe door edges during closing movement haveito ride over themor such bea'ds might be provided" on both the-door and the appositioned ;.edges ofeother partslin some styleof staggered tion'from propershape of concave-convex sheet 5 xernplifiedby the drawingr design) the beads protide spacehbetween the .appositioned edges 01' double contributing vutility, first, to permit ap- 1 ;,,pli cation of anautomaticallythinnerspray apstages. 'We have long hoped'to :devise armeans by which an: assembled sheet metal heater casing ,plioationbf enamel sin a direction toward the .insideoflthacasing and upon appositioned edges 'at :such' spaceaand, second, to permit circulation Specific advantages of employment of my invention are:

1. Successfully to permit assembly of the com- *plete jacket-before enameling with the decided advanta ge-that the initial assembly of the steel parts can be effected without thecare .whichis absolutely necessary to be exercised if the vitreous glass-finish hasbeen' applied before assembly because of its likelihood of fracturing if bent, strained or subjected to an impact.

2. Accomplishing a marked reduction in the cost of enameling the heater if assembled instead of while its parts are disassembled. For example, in a 5 x 12 ft. box type furnace it is possible to burn about four times as many heaters per hour when they are previously assembled. The same saving may be realized in a continuous or any other type of furnace. The spraying operation is also greatly facilitated so that about double the number of heaters may be sprayed in any fixed time,

3. Distortion of the heater jacket is avoided by the temporarily maintained sprung-apart relationship along edges of the door which are appositioned either to the bottom, top or connecting wall.

4. The cleaning and necessary trimming of each heater jacket is greatly reduced by burning the heater according to my method because the parts have been previously fitted together and less wiping is required to reduce enamel fracture where two enamel parts meet as for instance, where a flue collar or water line fitting is ultimately to engage the vitreous glass finish.

5. By enameling the complete assembled heater, the enamel enters all permanently joined seams between the connecting wall and top and bottom which interposed enamel when fused presents a more finished appearance and adds to the rigidity. Moreover all the parts are necessarily matched for color without the need of time-consuming selection and additionally all bolt and screw heads become enamel-coated with color match to realize economy and a better appearance as compared with a nickel or chrome finish on the stove bolt units.

Adverting to the drawing:

Figure 1 is a vertical, diametric sectional view of a water heater jacket embodying the principles of my invention.

Figure 2 is a correspondingsectional View taken at an angle of 90 with reference to the section line on which Figure 1 is viewed and may be considered as on line 22 of Figure 1.

Figure 3 is an enlarged horizontal section on line 3-3 of Figure 2 to illustrate how the temporary spacing beads cause appositioned edges to yield apart.

Figure 4 is a horizontal section on line 44 of Figure 2.

Figure 5 is a view corresponding to Figure 3 of a modification wherein the flanges of the door are provided with beads, instead of having them on the wall margins.

It is iterated that the principle of my invention is realized to be applicable to many articles of diiferent shape and function and that the spreading apart of certain edges which interlap need not include a door and that if a door or other equivalent complemental and displaceable member be employed it need not necessarily be hinged.

The exemplifying illustration of a water heater casing or jacket comprises a perforated or reticulated base 1 comprising an annular outer margin and a depressed central portion 1a between which are openings 11). A top plate 2 is fashioned with a hot water outlet 3 at one side and with a central upstanding-flanged opening 4 around which a flue pipe is to rest. A substantially semicylindric wall 5 connects the base and top it being provided with inwardly extending flanges 6 with which stove bolts 7 effect the connection. A coma, plementarily shaped door 8 is hinged to the wall 5 by means of hinge pins 9 which pass through overlying pairs of ears 10 on the wall and door respectively.

The four parts 1, 2, 5 and 8 which define the shape of the jacket are all of limited resiliency inherent in rather thin sheet metal stampings so that the arcuate halves of the base and top which are not attached to the wall 5 may be flexed relative to each other and so that the pairs of vertical margins of the wall 5 and door 8 may be slightly moved toward or away from each other. The drawing discloses the vertical edges of the door to be fashioned with offset flanges 11 which are to enclose the margins of the wall when the door is closed and each of such wall margins in Figure 2 is clearly shown to be fashioned with a row of four outwardly projecting beads 12 adapted during the final closing movement of the door to be ridden over by the flanges of the door 8 as shown in Figure 3 whereby slightly to move the margins of the wall toward each other and whereby slightly to spread the flanged vertical margins of the door. One series of four beads 12 along the hinge axis are also indicated by dotted lines in Figure 1. I

The arcuate top and bottom flanged margins of the door which are respectively to underlie and overlie the arcuate marginal portions of the top and base which are not attached to the wall 5,

are also fashioned with one or more vertically projecting beads 13 adapted, when the door ap proaches its closed position, to slightly raise the appositioned portion of the top and to spread apart the appositioned bottom door edge and base. Such beads 13 are disclosed in Figure 1.

It will be observed that space 14 is provided between the vertical margins of the wall and door when appositioned and spaced 15 provided between the top and bottom edges of the door and the top and base respectively whereby the desirable heat circulation past all appositioned edges may occur during the baking operation.

In practice, the heater jacket is completely assembled and then while the door is ajar both the 1 inside and outside surfaces are sprayed with a ground coat of enamel which is then baked while the door is closed and allowed to cool. Next, the door is closed, the finish or color coat is sprayed to all outside surfaces. It was happily discovered that the spraying operation would result in an application of the fluid enamel between the spaced appositioned edges as a progressively thinner coating in a direction from the outside toward the inside to realize the advantage of the avoidance of a surplus accumulation of enamel between appositioned edges and thereby eliminate a wiping operation heretofore required to avoid friable points of excess enamel likely to fracture after being baked. The provision of the spaces 14 and 15 as an incident to the desirable temporary sprung-apart relationship of all appositioned edges affords the desirable circulation therethrough of heat while in the oven to effect a more uniform baking of the vitreous enamel at the same time that the temporary sprung-apart relationship maintains the desired shape of the whole.

The modification of Figure 5 is merely to illustrate the feasibility of having beads 16 fashioned along both inner margins of the door 8 instead of along the outside of both marginal edges of the wall 5. A similar alternative might be adopted of substituting for the beads 13 on the top and bottom edges of the door one or more beads on the door-appositioned margins of the top and base.

' Finally, the beads may be ground off or enough reduced to insure an unresisted door opening and closing movement.

It is to be realized that the scope of my invention comprehends many equivalent methods and constructions. The showing of the drawing and the particular description are merely specific exemplifications of a plurality of mechanical embodiments and arrangements.

I claim:

1. The method of enameling a hollow article having a hinged door, which comprises holding apart the meeting edges of the door and structure to which said door is hinged, applying an enamel coating and then baking while the door is closed with appositioned edges sprung apart to facilitate heat circulation therebetween.

2. The method of enameling a hollow article having a hinged door, which comprises temporarily holding apart the meeting edges of the door and structure to which said door is hinged, spraying an enamel coating to the article, baking while the door is closed and then allowing the article to cool while the door is closed.

3. The method of enameling and baking a cylindrical metal casing composed of a bottom, top semi-cylindrical connecting wall and semi-cylindrical door hinged to said wall, which comprises forming predeterminately spaced beads on certain edges to be appositioned when the door is closed for forcing and holding apart said somewhat resilient edges, spraying an enamel coating upon the assembled parts, baking, allowing the whole to cool and then removing the beads.

4. The method of enameling and baking a composite, assembled cylindrical metal casing composed of a circular bottom, circular top, semicylindrical connecting wall, and semi-cylindrical door hinged to one upright edge of said wall, interposing spacer members between somewhat resilient edges of certain of the assembled parts when appositioned with the door in its closed position, then spraying an enamel coating over all to achieve a progressively thinner layer thereof between appositioned edges and finally baking while the door is closed to allow heat circulation between said appositioned edges while frustrating warpage by the sprung interengagement at appositioned edges. I

5. The method of enameling an article including a door, comprising the inter-positioning of spacer means between the appositioned door edges and the margins of the door opening, applying an enamel coating, baking and then removing said spacer means.

6. The method of enameling a hollow metal article including a hingedly connected door, comprising the interpositioning of wedges at predeterminately spaced points between the door edges and the margins of the door opening as appositioned when the door is closed, spraying an enamel coating to exterior surfaces and to said edges and margins, baking and then removing said wedges.

'7. The method of enameling a metal heater casing comprising a top, a bottom, partial connecting wall and complemental door with each specified casing part of limited resilience, comprising the interpositioning of wedges at predeterminately spaced points between certain door edges and certain relatively appositioned margins of the door opening whereby to spring theappo- G5 sitioned edges to temporarily desired positions while providing space therebetween, spraying an enamel coating on exterior surfaces and into said provided space, baking while allowing heat circulation through said space, cooling and then 1L3 removing the wedges.

8. The method of enameling a composite metal article with edges of limited resiliency including a part movable relatively to another part, com prising the establishment of a temporarily it; sprung-apart relationship between certain of said edges, applying an enamel coating, baking allowing to cool and finally releasing the sprung-apart relationship.

9. The method of enameling a composite article comprising resilient sheet metal parts one of which is interfitted with and movable relatively to other parts, comprising the establishment of a temporarily sprung-apart relationship between certain areas of some of said parts, spraying an enamel coating to achieve a progressively thinner application on said appositioned areas, baking, allowing to cool and finally releasing the sprung-apart relationship.

10. The method of enameling a composite article comprising resilient sheet metal parts one of which is interfitted with and movable relatively to other parts, comprising the temporarily interpositioning wedges between certain appositioned areas of some of said parts to increase the space therebetween spraying an enamel coating, baking, allowing to cool and finally removing said wedges.

ALBERT W. MACKERT. 

